The security company that employed Orlando nightclub killer Omar Mateen was fined $151,400 Friday for falsely listing psychological testing information on more than 1,500 forms that allowed employees to carry guns.

The Florida Department of Agriculture and Consumer Services imposed the fine after discovering G4S Secure Solutions had listed the name of a psychologist who no longer practiced as the screener on Mateen's form and those of many others over a 10-year period.

The Palm Beach Gardens-based company had employed Mateen for nine years as an armed security guard before his June 12 shooting rampage at Pulse, a gay nightclub, where he killed 49 people. He was shot to death by police.

Among his jobs at G4S was to guard the St. Lucie County Courthouse, where he worked the metal detector, and at the PGA Village gated community, where he stood in the booth that checked in visitors.

Although his motives may never be known, Mateen, who lived in Fort Pierce, had been investigated for possible terrorist ties and during the shooting announced his allegiance to the Islamic State.

As Mateen's background came under scrutiny after the attack, it was revealed that G4S had filed a form on his behalf to allow him to carry a gun as a security guard. The form, dated Sept. 6, 2007, stated that psychologist Carol Nudelman had administered his mental health test.

But Nudelman had retired nearly two years before the form was filed, selling her practice and moving out of state. She issued a statement saying she had never tested Mateen. Another psychologist had conducted the evaluation.

The Department of Agriculture opened an investigation, going through thousands of certification forms filed by G4S. Investigators found a total of 1,514 forms submitted between 2006 and 2016 that erroneously listed Nudelman's name. The fine amounts to $100 per violation.

Jennifer Meale, spokeswoman for the department, said there was no indication Nudelman was involved. She also said the department was satisfied that the psychological evaluations had actually been carried out, just by another psychologist.

"Our investigation revealed that, while a psychologist reviewed character certifications for G4S, the company's use of preprinted forms resulted in inaccurate information being reported to our department," she said.

"This is the largest fine issued in history" under this section of the law, Meale said.

The company issued a statement Friday evening saying it "cooperated fully" with the investigation.

"Due to an administrative error, Dr. Nudelman's name appeared erroneously on license applications," the company said. "As soon as this error became known to G4S, it immediately and publicly acknowledged that this was an administrative error and took measures to ensure that this error would not be repeated."

Nudelman, who now lives in Colorado, could not be reached for comment.

The company originally blamed a "clerical error" for the erroneous listing of Nudelman's name on Mateen's form.

The signature of a G4S manager appeared on the form, which stated "This document is executed under oath. Falsification or misrepresentation subjects the person completing the document to criminal prosecution under Section 837.06, Florida Statutes."